In only twenty years, mobile phones, also referred to as cellular phones, have gone from obscure and expensive gadgets to phenomenally common and low-cost personal commodities.
At the same time, a new mobile lifestyle enabled by mobile phones has emerged. People use mobile phones to keep in touch with family and friends while on-the-go. Popular features such as Short Message Service (SMS), camera and music further solidify cellular phones as must-have items for consumers.
With the addition of Internet access, availability of WiFi hotspots, and popularity of Instant Messaging, a new breed of dual-mode mobile phones has arrived. Besides cellular telephone service, these new dual-mode mobile phones can receive Instant Messaging (IM) based telephone services such as Yahoo! Messenger with Voice network, Google Talk, American Online (AOL) Instant Messenger Phoneline Service and Skype by connecting to a private WiFi access point at home, or by connecting to a public WiFi access point at a hotspot. These IM-based telephone services oftentimes provide alternative voice service and advanced features that complement the cellular counterpart.
As these IM-based telephone services are commonly adopted by dual-mode mobile phone users, a new problem surfaces: IM-based voice calls are dropped as soon as a user is out of range of a WiFi access point or hotspot. For example, in one scenario an individual lives in a neighborhood with good cellular coverage. He subscribes broadband service from the local cable company and has installed a WiFi access point for convenience. He recently purchased a dual-mode mobile phone and begins using Yahoo Messenger with Voice service at home. The individual particularly enjoys chatting with his mother in Budapest using the IM-based voice network Yahoo Messenger with Voice in the evening while walking his dog. Unfortunately, the phone call is abruptly cut off whenever he walks beyond the coverage of his WiFi access point. The individual must make a cellular phone call to resume the conversation.
In another scenario, on a typical day before heading to work, another dual-mode phone user enjoys having a cup of coffee at a downtown café that provides hotspot Internet access. Usually, the user uses her dual-mode mobile phone to make several SKYPE phone calls over the Hotspot to start the day. In one instance, the user calls a local utility company to file a complaint. After waiting 15 minutes for a utility company customer service representative, and at which time the user needs to leave for work, she is connected to a customer service representative. To her dismay, the SKYPE phone call is disconnected when she leaves the café and walks to her car in the parking lot.
Therefore, there is a need to provide a system and method to switch a voice call from an IM voice network to a cellular voice network.